The present invention relates to an electrical connector, and particularly to a Land Grid Package (LGP) electrical connector designed to reduce the bending moment acting on each soldered connection between each contact of the LGP and a printed circuit board.
Ball Grid Array (BGA) chips were introduced having ball-like solders on a bottom face thereof, whereby each BGA chip is secured to a printed circuit board. However BGA chips have several disadvantages, including a complicated manufacture and high cost. Land Grid Package (LGP) chips were later introduced having plate-type electrodes on a bottom face thereof. LGP chips are easier to manufacture and much lower in cost than BGA chips.
LGP chips electrically connect to a printed circuit board via an LGP electrical connector. The LGP electrical connector comprises a plurality of metal contacts each of which has a base soldered to a printed circuit board, and an upper contact portion depressed by and engaging with a corresponding electrode of an LGP chip, whereby the chip and the printed circuit board are electrically connected together by the connector.
A contact 16 of an LGP electrical connector from U.S. Pat. No. 4,553,192 is shown in FIG. 10. The contact 16 has a U-shaped configuration and comprises a spring contact beam 26 and a lower portion 27 extending in a same direction. A soldering base 28 extends from a distal end of the lower portion 27 for soldering to a first circuit pad 15 of a printed circuit board (not shown). The spring contact beam 26 is depressed by and engages with a second circuit pad 20 of an integrated circuit module 17. The depressing force of the chip on the contact induces a bending moment in the soldering base 28, which causes the soldering base 28 to have a tendency to disengage from its soldering. Therefore, an improved LGP connector is needed which can effectively reduce the induced bending moment acting on the soldering bases of the contacts of the connector when an LGP chip is mounted on the connector.